Electron-ion collider in China

Abstract

Lepton scattering is an established ideal tool for studying inner structure of small particles such as nucleons as well as nuclei. As a future high energy nuclear physics project, an Electron-ion collider in China (EicC) has been proposed. It will be constructed based on an upgraded heavy-ion accelerator, High Intensity heavy-ion Accelerator Facility (HIAF) which is currently under construction, together with a new electron ring. The proposed collider will provide highly polarized electrons (with a polarization of ∼80%) and protons (with a polarization of ∼70%) with variable center of mass energies from 15 to 20 GeV and the luminosity of (2–3) × 1033 cm−2 · s−1. Polarized deuterons and Helium-3, as well as unpolarized ion beams from Carbon to Uranium, will be also available at the EicC.The main foci of the EicC will be precision measurements of the structure of the nucleon in the sea quark region, including 3D tomography of nucleon; the partonic structure of nuclei and the parton interaction with the nuclear environment; the exotic states, especially those with heavy flavor quark contents. In addition, issues fundamental to understanding the origin of mass could be addressed by measurements of heavy quarkonia near-threshold production at the EicC. In order to achieve the above-mentioned physics goals, a hermetical detector system will be constructed with cutting-edge technologies.This document is the result of collective contributions and valuable inputs from experts across the globe. The EicC physics program complements the ongoing scientific programs at the Jefferson Laboratory and the future EIC project in the United States. The success of this project will also advance both nuclear and particle physics as well as accelerator and detector technology in China.

Higher-order kinematical effects in deeply virtual Compton scattering

“…Therefore, the DVCS cross-section measurements that allow us to measure the CFFs and reconstruct the GPDs play an important role in studying the internal structure of the nucleon. There have been measurements from HERA (H1 [12][13][14][15], ZEUS [16,17] and HERMES [18,19]) and Jefferson Lab (JLab) (CLAS [20,21] and Hall A [22,23]) and more programs are planned in the future such as the JLab 24 GeV, EIcC [24] and EIC [25]. Those cross-section measurements as well as lattice calculations are crucial in order to understand the nucleon three-dimensional structure.…”

Twist-2 relation and sum rule for tensor-polarized parton distribution functions of spin-1 hadrons

“…The NICA facility will have the polarized-deuteron beam in the near future [21,22], so that they could focus their studies on the structure functions of the spin-1 deuteron. In addition, there are EIC projects in US and China [12,13] to investigate the structure functions of the spin-1 hadrons and nuclei in 2030's. In the JLab measurements, the scale Q 2 is not large in general, which enables to probe the twist-3 structure functions such as g 2 .…”

“…It is expected to be measured by an JLab experiment [9][10][11]. These b 1 and ∆ T g measurements could be continued at the electron-ion collider (EIC) [12] and the Electron-ion collider in China (EicC) [13].…”

Angularity in DIS at next-to-next-to-leading log accuracy

“…Deep inelastic scattering (DIS) [1][2][3][4][5] is an important tool to probe internal structure of nucleus and to test our understanding of Quantum Chromodynamics (QCD) [6,7]. Newly proposed future electron-ion collider (EIC) [8,9] and electron-ion collider in China (EicC) [10] would provide another opportunities to test and to improve our understanding of the structure of nuclei as well as dynamics of QCD in collisions.…”